Abstract
The roles that leaf nitrate content and nitrate flux play in regulating the levels of nitrate reductase activity (NRA) were investigated in 8- to 14-day old maize (Zea mays L.) plants containing high nitrate levels while other environmental and endogenous factors were constant. The nitrate flux of intact plants was measured from the product of the transpiration rate and the concentration of nitrate in the xylem. NRA decreased when the seedlings were deprived of nitrate. The nitrate flux and the leaf nitrate content also decreased. When nitrate was resupplied to the roots, all three parameters increased.Attempts to alter the nitrate flux by varying transpiration rates were unsuccessful due to a relatively constant rate of delivery of nitrate to the xylem as transpiration rates fell. However, cooling the roots resulted in a decrease in the nitrate flux. Plants with a lower nitrate flux rapidly lost NRA, although the leaf nitrate content was initially unaffected. If the roots remained cool for a long enough time, the leaf nitrate content eventually decreased. Rewarming the roots increased the nitrate flux, leaf nitrate content, and NRA to control levels. When the nitrate flux in excised shoots was varied in three separate ways, decreasing the nitrate flux to the leaves resulted in a rapid decrease in NRA, although leaf nitrate contents were unchanged.These experiments show that the nitrate flux to the leaves from the roots plays a much larger regulatory role than the leaf nitrate content in controlling the level of NRA in intact plants.
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Claims 11
Claim · model-written summary
Nitrate deprivation decreased nitrate reductase activity (NRA) in maize seedlings.
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e1“NRA decreased when the seedlings were deprived of nitrate”
Claim · model-written summary
Nitrate deprivation decreased the nitrate flux and leaf nitrate content.
- Treatment
- deprived of nitratee1
- Outcome
- nitrate flux and the leaf nitrate contente2
- Direction
- decreasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e1“NRA decreased when the seedlings were deprived of nitrate”
e2“The nitrate flux and the leaf nitrate content also decreased”
Claim · model-written summary
Resupplying nitrate to the roots increased all three parameters: NRA, nitrate flux and leaf nitrate content.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e3“When nitrate was resupplied to the roots, all three parameters increased”
Claim · model-written summary
Root cooling decreased nitrate flux.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e4“cooling the roots resulted in a decrease in the nitrate flux”
Claim · model-written summary
Plants with a lower nitrate flux lost NRA rapidly, while leaf nitrate content was initially unaffected.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e5“Plants with a lower nitrate flux rapidly lost NRA, although the leaf nitrate content was initially unaffected”
Claim · model-written summary
When roots remained cool long enough, leaf nitrate content eventually decreased.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e6“If the roots remained cool for a long enough time, the leaf nitrate content eventually decreased”
Claim · model-written summary
Rewarming the roots restored nitrate flux, leaf nitrate content and NRA to control levels.
- Treatment
- Rewarming the rootse7
- Outcome
- nitrate flux, leaf nitrate content, and NRAe7
- Direction
- increasede7
- Comparator
- control levelse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e7“Rewarming the roots increased the nitrate flux, leaf nitrate content, and NRA to control levels”
Claim · model-written summary
Decreasing nitrate flux to the leaves rapidly decreased NRA.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e1“decreasing the nitrate flux to the leaves resulted in a rapid decrease in NRA, although leaf nitrate contents were unchanged”
Claim · model-written summary
Decreasing nitrate flux to the leaves left leaf nitrate contents unchanged.
- Treatment
- decreasing the nitrate flux to the leavese1
- Outcome
- leaf nitrate contentse1
- Direction
- no_changeinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e1“decreasing the nitrate flux to the leaves resulted in a rapid decrease in NRA, although leaf nitrate contents were unchanged”
Claim · model-written summary
Varying transpiration rates did not alter nitrate flux.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e2“Attempts to alter the nitrate flux by varying transpiration rates were unsuccessful”
Claim · model-written summary
Nitrate flux to the leaves from the roots plays a much larger regulatory role than leaf nitrate content in controlling NRA in intact maize plants.
- Treatment
- nitrate flux to the leaves from the rootse3
- Outcome
- level of NRAe3
- Qualifier
- plays a much larger regulatory role than the leaf nitrate contente3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were investigated in 8- to 14-day old maize (Zea mays L.) plants”
e3“These experiments show that the nitrate flux to the leaves from the roots plays a much larger regulatory role than the leaf nitrate content in controlling the level of NRA in intact plants”
The same questions in other papers
nitrogen · nutrient: content · Zea mays (maize)Positive and negative results
85 papers in the same direction as this paper · 403 in the opposite direction
- positive
- positive
- positive
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